Observatory network

A planet-spanning detector array

No single detector can pinpoint where a gravitational wave came from. By comparing the arrival time and strength of a signal across detectors on different continents, scientists can triangulate its position on the sky.

LIGO Hanford

United States

4 km dual-arm interferometer in the Pacific Northwest.

Operational

LIGO Livingston

United States

4 km interferometer ~3,000 km from Hanford.

Operational

Virgo

Italy

3 km European detector run by the EGO consortium.

Operational

KAGRA

Japan

Underground, cryogenic 3 km interferometer.

Operational

LIGO-India

India

Planned 4 km detector to widen the global network.

Under construction

Confirmation

Independent detectors rule out local noise — a real signal appears in multiple instruments.

Sky localization

Time differences between sites narrow down the patch of sky a wave came from.

Multi-messenger

Tighter localization helps telescopes point quickly to catch any accompanying light.